Heavy-flavor parton distributions without heavy-flavor matching prescriptions

TL;DR

This paper proposes a method to improve heavy-flavor parton distribution functions by adjusting the heavy flavor matching point, reducing power correction errors, and maintaining resummation accuracy without additional prescriptions.

Contribution

It introduces a novel approach of choosing a larger heavy flavor matching point to enhance the zero-mass scheme's accuracy and continuity in predictions.

Findings

Choosing a larger HFMP reduces power correction errors.

The method maintains resummation accuracy without extra prescriptions.

Predictions for collider processes show broad applicability.

Abstract

We show that the well-known obstacle for working with the zero-mass variable flavor number scheme, namely, the omission of O(1) mass power corrections close to the conventional heavy flavor matching point (HFMP) mu_b=m, can be easily overcome. For this it is sufficient to take advantage of the freedom in choosing the position of the HFMP. We demonstrate that by choosing a sufficiently large HFMP, which could be as large as 10 times the mass of the heavy quark, one can achieve the following improvements: 1) above the HFMP the size of missing power corrections O(m) is restricted by the value of mu_b and, therefore, the error associated with their omission can be made negligible; 2) additional prescriptions for the definition of cross-sections are not required; 3) the resummation accuracy is maintained and 4) contrary to the common lore we find that the discontinuity of alpha_s and pdfs across thresholds leads to improved continuity in predictions for observables. We have considered a large set of proton-proton and electron-proton collider processes, many through NNLO QCD, that demonstrate the broad applicability of our proposal.